The purpose of this research is to identify specific oral-facial variations present in the near relatives (1st and 2nd degree) of cleft lip and palate probands. This is a continuation of the project begun 3 years ago to identify non-cleft persons with major genetic liability for transmitting the trait to offspring. However, we now have a major shift in our working hypothesis. Instead of studying all relatives of clefts for oral-facial variations, as is compatible with the accepted multifactorial model of causation of cleft lip and palate, we will study only relatives in multiply affected families, and only those in unilateral lines, for evidence of clefting gene action. The reason for this approach is data we have recently obtained denies multifactorial inheritance and supports the presence of a monogenic, dominantly inherited form of cleft palate within the heterogeneous group of palatal clefts. Hence, our use of multiply affected families limits the investigation to a single cleft type, the one most likely to yield a positive result. The same reasoning applies to the study of clefts of the primary palate. In this study, a series of 15-20 families with at least 2 affecteds in near relatives will be evaluated for (1) morphologic and (2) functional (speech) variations as evidence of minor expression of a monogenic trait. Such minor expressions will be most useful to the genetic counselor in providing recurrence risks for affected families.